In a variety of wellbore environments, electric submersible pumping systems are used to lift fluids from a subterranean location. Although electric submersible pumping systems can utilize a wide variety of components, examples of basic components comprise a submersible pump, a submersible motor and a motor protector. The submersible motor powers the submersible pump, and the motor protector seals the submersible motor from well fluid. The motor protector also balances the internal motor oil pressure with external pressure.
Motor protectors often are designed with a labyrinth system and/or an elastomeric bag system. The labyrinth system uses the difference in specific gravity between the well fluid and internal motor oil to maintain separation between the fluids. The elastomeric bag system relies on an elastomeric bag to physically isolate the motor oil from the well fluid while balancing internal and external pressures. Additionally, motor protectors often have an internal shaft that transmits power from the submersible motor to the submersible pump. The shaft is mounted in journal bearings positioned in the motor protector.
Such protectors function well in many environments. However, in abrasive environments, the runlife of the motor protector can be detrimentally affected. The abrasive sand causes wear in motor protector components, such as the journal bearings. Attempts have been made to increase runlife by populating the motor protector with journal bearings made from extremely hard materials to reduce wear caused by the abrasive sand.